In the prior art the transducing head is mounted on a flexible longitudinal leaf member, the leaf member mounted as a cantilever beam, secured at one end to a mounting base to extend outwardly from the base and support a transducing head at the free end of the beam. In the helical-scan magnetic tape transport art, one or more of these leaf-type members may be used, each mounted at the interior of a rotating drum, to extend radially toward the periphery of the drum, the head protruding through an opening in the drum to traverse or scan the recorded tracks on a magnetic tape curved around the periphery of the drum in a helical path.
A mounting arrangement as described above typically incorporates a mechanism for driving the leaf member, such as a voice coil assembly interactive with the leaf member for positioning the head by means of a feedback circuit connected between a head positioning apparatus and the voice coil assembly. However, a significant disadvantage of such a head positioning arrangement is the limitation of head positioning parameters to relatively low speed displacements, since the relatively long and thin head positioning member will not uniformly bend at high speeds. That is, the inherent flexibility of the long, thin head positioning member sets up undesirable resonances in the member under rapid and repetitive flexure loadings. Such resonances also result in undesirable changes in the bending moment under repeated flexures of such member. The occurrence of such conditions in the member under the desired loading sequence severely impairs the ability of a head mounted on the member to follow a tape track recorded on a magnetic tape.
One prior art support structure for a transducing head is shown in U.S. Pat. No. 4,212,043 by Baker entitled "Magnetic Transducing", issued Jul. 8, 1980 and assigned to the assignee of the present invention.
However, that patent, although displaying a more stable structure presents a structure which is directed to controlling the movement of a head stack having multiple heads disposed adjacent a magnetic tape. The movement of a head stack has to be parallel to the plane of the tape to enable each head in the stack to follow a respective track on the tape. A single head mounted on a leaf member is positioned to engage a single tape track, and positioning of that single head by a cantilever bending element is viable because of the relatively small displacements involved. Further, the patented structure is also directed to solve certain problems introduced by centrifugal forces bearing against the support structure and not problems relating to rapid and repetitive displacement of the transducing heads. Moreover, the structure of the device described in the aforementioned patent is not amenable to the swift and repeated displacements required in a system directed to the rapid processing of data, i.e., a digital tape transport.